Cured silicone powders are used as additives in, for example, cosmetics, paints, inks, thermosetting organic resins, and thermoplastic organic resins. Cured silicone powders are particularly well suited for use as internal stress relaxers for thermosetting organic resins and as surface lubricants for organic resin films.
Cured silicone powders can be produced, for example, by grinding silicone rubber, by curing a liquid silicone rubber composition while spray drying (refer to Japanese Patent Application Laid Open Number Sho 59-68333 (68,333/1984), and by curing a liquid silicone rubber composition while it is dispersed in water (refer to Japanese Patent Application Laid Open Numbers Sho 62-243621, Sho 63-77942, Sho 63-202658, and Sho 64-70558. However, the cured silicone powders afforded by these methods have a strong tendency to aggregate and, as a result, have a poor flowability. Further, they cannot be uniformly dispersed in organic resins, e.g., thermosetting organic resins and thermoplastic organic resins.
Composite cured silicone powders with an improved flowability have been proposed in order to solve these problems. These composite cured silicone powders comprise cured silicone powder whose surface has been coated with a microfine inorganic powder (refer to Japanese Patent Application Laid Open Numbers Hei 4-348143, Hei 5-179144, and Hei 7-102075). These composite cured silicone powders, however, exhibit a poor water repellency and thus have a poor affinity for organic resins in those applications where they are blended with organic resins.